What is it about?

Over the last decade, carbon materials have emerged as an environmentally friendly and metal-free catalyst option for a range of reactions. This article presents a novel, metal-free method for synthesizing biaryl compounds via carbocatalyzed oxidative dehydrogenation (ODH). The proposed method uses a commercially available active carbon as the catalyst, which is simply treated by air to increase its surface oxygen content. The obtained oxidized carbon material is revealed to exhibit exceptional activity for the oxidative aromatization of aryl cyclohexenes, comparable to certain metal catalysts. Through a series of experiments, including selective blocking of functional groups on the carbon surface, and the use of molecular model compounds, we are able to identify the quinoidic groups on the carbon surface as the catalytic active sites, and, studying the reaction kinetics and substrate scope, to propose a mechanism for the reaction.

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Why is it important?

Biaryls serve as a common structural unit within a diverse range of fine chemicals and are prevalent components in natural products. The carbocatalyzed oxidative dehydrogenation (ODH) reaction offers a promising metal-free method for producing biaryls from cyclic alkanes. While carbon-based catalysts have been developed to enable more environmentally benign olefin production, their potential as catalysts for biaryl synthesis remains less explored.

Perspectives

We firmly believe that carbon materials are promising catalysts for a wide variety of chemical reactions. and will play a crucial part in the transition towards more environmentally friendly chemical production, reducing our reliance on precious metals. We aspire to deepen our understanding of carbon materials' properties and their catalytic mechanism of action, to be able to harness their capabilities for broader applications.

Mingze Yang
Aalto-yliopisto

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This page is a summary of: A metal-free carbon catalyst for oxidative dehydrogenation of aryl cyclohexenes to produce biaryl compounds, Proceedings of the National Academy of Sciences, July 2023, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2303564120.
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